And are monitored at the Wastewater Treatment Plant near Solvang.
The county said West Nile virus is most commonly spread to people by mosquito bites.
"This time of the year, the risk of West Nile virus infection increases and individuals should take precautions to avoid mosquito bites and eliminate potential mosquito breeding sites", said ODH State Epidemiologist and Bureau Chief of Infectious Diseases Sietske de Fijter.
So far this year cases have been reported in Bolivar, Calhoun (2), Clarke, Clay, Covington, DeSoto, Forrest (5), Hinds (13), Humphreys (2), Jones, Lauderdale, Leake, Lee (3), Leflore, Lincoln (2), Lowndes (2), Madison (4), Monroe (2), Noxubee, Perry, Rankin (7), Scott (2), Sunflower, Wilkinson, and Yazoo counties. "Most humans who become infected with WNV do not get sick".
However, in elderly people and those with suppressed immune systems the virus can be deadly.
Residents are asked to take their own initiative to help reduce mosquito populations by emptying standing water on their property and to wear long sleeves and use repellents according to the label when outdoors.
Ensure that door and window screens are tight-fitting and in good fix.
County health officials urged the public to remain vigilant against mosquitoes until there's a mosquito-killing frost this year, and they urged horse owners to vaccinate their horses against EEE. Mosquitoes can breed in as little as one quarter inch of standing water.